An AC motor is a device that converts electrical energy into mechanical energy, mainly by driving the rotor of the motor to rotate through the input of alternating current. In an AC motor, there are two main parts: the stator and the rotor.

The stator is the stationary part of the motor and usually consists of electromagnetic coils. When an electric current passes through the stator's coils, it creates a magnetic field, which is a rotating magnetic field because the waveform of the alternating current changes periodically. The rotor, on the other hand, is the rotating part of the motor and usually consists of one or more conductor coils. When the stator generates a rotating magnetic field, it interacts with the conductor coils on the rotor, causing the rotor to begin to rotate.

The principle of operation of an AC motor is based on Faraday's law of electromagnetic induction and the Lorentz force. According to Faraday's law of electromagnetic induction, when a coil of conductors rotates in a magnetic field, an induced electromotive force is generated within the coil of conductors. This induced electromotive force produces a current that interacts with the magnetic field and generates the Lorentz force, which causes the conductor coil to rotate.

In order for an AC motor to work continuously and to produce a steady torque, an AC motor needs a commutator. The purpose of the commutator is to change the direction of the current in the stator coils, which in turn changes the direction of the magnetic field. The commutator required for an AC motor is usually a device called a rectifier, which converts alternating current to direct current. The DC current can be controlled by the commutator so that the direction of the current in the stator coils changes, thus changing the direction of the magnetic field.

The design and function of the commutator is critical to the proper operation of an AC motor. It ensures that the motor will work continuously and will produce sufficient torque as the rotor rotates. The commutator can be implemented in a variety of ways, including the use of mechanical brushes or electronic commutators.

To summarize, AC motors work through the interaction between a magnetic field and an electric current. The stator generates a rotating magnetic field, and this field interacts with the conductor coils on the rotor, which causes the rotor to start rotating. For proper operation of an AC motor, a commutator is used to change the direction of the current in the stator coils and thus the direction of the magnetic field. The design and function of the commutator is critical to the performance and efficiency of the motor.